text: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef COMPONENTS_UI_ZOOM_ZOOM_CONTROLLER_H_
  #define COMPONENTS_UI_ZOOM_ZOOM_CONTROLLER_H_
  
  #include "base/basictypes.h"
  #include "base/compiler_specific.h"
  #include "base/memory/ref_counted.h"
  #include "base/memory/scoped_ptr.h"
  #include "base/observer_list.h"
  #include "base/prefs/pref_member.h"
  #include "content/public/browser/host_zoom_map.h"
  #include "content/public/browser/web_contents_observer.h"
  #include "content/public/browser/web_contents_user_data.h"
  
  class ZoomControllerTest;
  
  namespace content {
  class WebContents;
  }
  
  namespace ui_zoom {
  class ZoomObserver;
  
  class ZoomRequestClient : public base::RefCounted<ZoomRequestClient> {
   public:
    ZoomRequestClient() {}
  
   protected:
    virtual ~ZoomRequestClient() {}
  
   private:
    friend class base::RefCounted<ZoomRequestClient>;
  
    DISALLOW_COPY_AND_ASSIGN(ZoomRequestClient);
  };
  
  // Per-tab class to manage zoom changes and the Omnibox zoom icon.
  class ZoomController : public content::WebContentsObserver,
                         public content::WebContentsUserData<ZoomController> {
   public:
    // Defines how zoom changes are handled.
    enum ZoomMode {
      // Results in default zoom behavior, i.e. zoom changes are handled
      // automatically and on a per-origin basis, meaning that other tabs
      // navigated to the same origin will also zoom.
      ZOOM_MODE_DEFAULT,
      // Results in zoom changes being handled automatically, but on a per-tab
      // basis. Tabs in this zoom mode will not be affected by zoom changes in
      // other tabs, and vice versa.
      ZOOM_MODE_ISOLATED,
      // Overrides the automatic handling of zoom changes. The |onZoomChange|
      // event will still be dispatched, but the page will not actually be zoomed.
      // These zoom changes can be handled manually by listening for the
      // |onZoomChange| event. Zooming in this mode is also on a per-tab basis.
      ZOOM_MODE_MANUAL,
      // Disables all zooming in this tab. The tab will revert to default (100%)
      // zoom, and all attempted zoom changes will be ignored.
      ZOOM_MODE_DISABLED,
    };
  
    enum RelativeZoom {
      ZOOM_BELOW_DEFAULT_ZOOM,
      ZOOM_AT_DEFAULT_ZOOM,
      ZOOM_ABOVE_DEFAULT_ZOOM
    };
  
    struct ZoomChangedEventData {
      ZoomChangedEventData(content::WebContents* web_contents,
                           double old_zoom_level,
                           double new_zoom_level,
                           ZoomController::ZoomMode zoom_mode,
                           bool can_show_bubble)
          : web_contents(web_contents),
            old_zoom_level(old_zoom_level),
            new_zoom_level(new_zoom_level),
            zoom_mode(zoom_mode),
            can_show_bubble(can_show_bubble) {}
      content::WebContents* web_contents;
      double old_zoom_level;
      double new_zoom_level;
      ZoomController::ZoomMode zoom_mode;
      bool can_show_bubble;
    };
  
    ~ZoomController() override;
  
    ZoomMode zoom_mode() const { return zoom_mode_; }
  
    // Convenience method to get default zoom level. Implemented here for
    // inlining.
    double GetDefaultZoomLevel() const {
      return content::HostZoomMap::GetForWebContents(web_contents())
          ->GetDefaultZoomLevel();
    }
  
    // Convenience method to quickly check if the tab's at default zoom.
    bool IsAtDefaultZoom() const;
  
    // Returns which image should be loaded for the current zoom level.
    RelativeZoom GetZoomRelativeToDefault() const;
  
    const ZoomRequestClient* last_client() const { return last_client_.get(); }
  
    void AddObserver(ZoomObserver* observer);
    void RemoveObserver(ZoomObserver* observer);
  
    // Used to set whether the zoom notification bubble can be shown when the
    // zoom level is changed for this controller. Default behavior is to show
    // the bubble.
    void SetShowsNotificationBubble(bool can_show_bubble) {
      can_show_bubble_ = can_show_bubble;
    }
  
    // Gets the current zoom level by querying HostZoomMap (if not in manual zoom
    // mode) or from the ZoomController local value otherwise.
    double GetZoomLevel() const;
    // Calls GetZoomLevel() then converts the returned value to a percentage
    // zoom factor.
    // Virtual for testing.
    virtual int GetZoomPercent() const;
  
    // Sets the zoom level through HostZoomMap.
    // Returns true on success.
    bool SetZoomLevel(double zoom_level);
  
    // Sets the zoom level via HostZoomMap (or stores it locally if in manual zoom
    // mode), and attributes the zoom to |client|. Returns true on success.
    bool SetZoomLevelByClient(
        double zoom_level,
        const scoped_refptr<const ZoomRequestClient>& client);
  
    // Sets the zoom mode, which defines zoom behavior (see enum ZoomMode).
    void SetZoomMode(ZoomMode zoom_mode);
  
    // content::WebContentsObserver overrides:
    void DidNavigateMainFrame(
        const content::LoadCommittedDetails& details,
        const content::FrameNavigateParams& params) override;
    void WebContentsDestroyed() override;
    void RenderFrameHostChanged(content::RenderFrameHost* old_host,
                                content::RenderFrameHost* new_host) override;
  
   protected:
    // Protected for testing.
    explicit ZoomController(content::WebContents* web_contents);
  
   private:
    friend class content::WebContentsUserData<ZoomController>;
    friend class ::ZoomControllerTest;
  
    void ResetZoomModeOnNavigationIfNeeded(const GURL& url);
    void OnZoomLevelChanged(const content::HostZoomMap::ZoomLevelChange& change);
  
    // Updates the zoom icon and zoom percentage based on current values and
    // notifies the observer if changes have occurred. |host| may be empty,
    // meaning the change should apply to ~all sites. If it is not empty, the
    // change only affects sites with the given host.
    void UpdateState(const std::string& host);
  
    // True if changes to zoom level can trigger the zoom notification bubble.
    bool can_show_bubble_;
  
    // The current zoom mode.
    ZoomMode zoom_mode_;
  
    // Current zoom level.
    double zoom_level_;
  
    scoped_ptr<ZoomChangedEventData> event_data_;
  
    // Keeps track of the extension (if any) that initiated the last zoom change
    // that took effect.
    scoped_refptr<const ZoomRequestClient> last_client_;
  
    // Observer receiving notifications on state changes.
    ObserverList<ZoomObserver> observers_;
  
    content::BrowserContext* browser_context_;
    // Keep track of the HostZoomMap we're currently subscribed to.
    content::HostZoomMap* host_zoom_map_;
  
    scoped_ptr<content::HostZoomMap::Subscription> zoom_subscription_;
  
    DISALLOW_COPY_AND_ASSIGN(ZoomController);
  };
  
  }  // namespace ui_zoom
  
  #endif  // COMPONENTS_UI_ZOOM_ZOOM_CONTROLLER_H_
  